1 /*
2 * Check decoding of socket filters.
3 *
4 * Copyright (c) 2017 Dmitry V. Levin <ldv@altlinux.org>
5 * Copyright (c) 2017-2018 The strace developers.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include "tests.h"
32
33 #include <stdio.h>
34 #include <unistd.h>
35 #include <netinet/in.h>
36 #include <sys/socket.h>
37 #include <linux/filter.h>
38
39 /* SO_GET_FILTER was introduced by Linux commit v3.8-rc1~139^2~518 */
40 #ifndef SO_GET_FILTER
41 # define SO_GET_FILTER SO_ATTACH_FILTER
42 #endif
43
44 #define HEX_FMT "%#x"
45
46 #if XLAT_RAW
47 # define XLAT_FMT HEX_FMT
48 # define XLAT_ARGS(a_) (a_)
49 #elif XLAT_VERBOSE
50 # define XLAT_FMT HEX_FMT " /* %s */"
51 # define XLAT_ARGS(a_) (a_), #a_
52 #else
53 # define XLAT_FMT "%s"
54 # define XLAT_ARGS(a_) #a_
55 #endif
56
57 #define PRINT_STMT(pfx, code_fmt, k_fmt, ...) \
58 printf("%sBPF_STMT(" code_fmt ", " k_fmt ")", pfx, __VA_ARGS__)
59
60 #define PRINT_JUMP(pfx, code_fmt, k, jt, jf, ...) \
61 printf("%sBPF_JUMP(" code_fmt ", %#x, %#x, %#x)", \
62 pfx, __VA_ARGS__, k, jt, jf)
63
64 static const struct sock_filter bpf_filter[] = {
65 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, SKF_LL_OFF+4),
66 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, SKF_NET_OFF+8),
67 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, SKF_AD_OFF+SKF_AD_PROTOCOL),
68 BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, IPPROTO_UDP, 0, 5),
69 BPF_STMT(BPF_LD|BPF_W|BPF_LEN, 0),
70 BPF_JUMP(BPF_JMP|BPF_K|BPF_JGE, 100, 0, 3),
71 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 42),
72 BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, 'a', 0, 1),
73 BPF_STMT(BPF_RET|BPF_K, -1U),
74 BPF_STMT(BPF_RET|BPF_K, 0)
75 };
76
77 static void
print_filter(void)78 print_filter(void)
79 {
80 PRINT_STMT("[", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
81 XLAT_FMT "+4",
82 XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
83 XLAT_ARGS(SKF_LL_OFF));
84 PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
85 XLAT_FMT "+8",
86 XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
87 XLAT_ARGS(SKF_NET_OFF));
88 PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
89 XLAT_FMT "+" XLAT_FMT,
90 XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
91 XLAT_ARGS(SKF_AD_OFF), XLAT_ARGS(SKF_AD_PROTOCOL));
92 PRINT_JUMP(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
93 IPPROTO_UDP, 0, 5,
94 XLAT_ARGS(BPF_JMP), XLAT_ARGS(BPF_K), XLAT_ARGS(BPF_JEQ));
95 PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
96 HEX_FMT,
97 XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_W), XLAT_ARGS(BPF_LEN),
98 0);
99 PRINT_JUMP(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
100 100, 0, 3,
101 XLAT_ARGS(BPF_JMP), XLAT_ARGS(BPF_K), XLAT_ARGS(BPF_JGE));
102 PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
103 HEX_FMT,
104 XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
105 42);
106 PRINT_JUMP(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
107 'a', 0, 1,
108 XLAT_ARGS(BPF_JMP), XLAT_ARGS(BPF_K), XLAT_ARGS(BPF_JEQ));
109 PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT,
110 HEX_FMT,
111 XLAT_ARGS(BPF_RET), XLAT_ARGS(BPF_K),
112 -1U);
113 PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT,
114 HEX_FMT,
115 XLAT_ARGS(BPF_RET), XLAT_ARGS(BPF_K),
116 0);
117 putchar(']');
118 }
119
120 static const char *errstr;
121
122 static int
get_filter(int fd,void * val,socklen_t * len)123 get_filter(int fd, void *val, socklen_t *len)
124 {
125 int rc = getsockopt(fd, SOL_SOCKET, SO_GET_FILTER, val, len);
126 errstr = sprintrc(rc);
127 return rc;
128 }
129
130 static int
set_filter(int fd,void * val,socklen_t len)131 set_filter(int fd, void *val, socklen_t len)
132 {
133 int rc = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, val, len);
134 errstr = sprintrc(rc);
135 return rc;
136 }
137
138 int
main(void)139 main(void)
140 {
141 int rc;
142 struct sock_filter *const filter =
143 tail_memdup(bpf_filter, sizeof(bpf_filter));
144 void *const efault = filter + ARRAY_SIZE(bpf_filter);
145 TAIL_ALLOC_OBJECT_CONST_PTR(struct sock_fprog, prog);
146 TAIL_ALLOC_OBJECT_CONST_PTR(socklen_t, len);
147
148 prog->len = ARRAY_SIZE(bpf_filter);
149 prog->filter = filter;
150
151 int fd = socket(AF_INET, SOCK_DGRAM, 0);
152 if (fd < 0)
153 perror_msg_and_skip("socket AF_INET SOCK_DGRAM");
154
155 /* query sock_filter program length -> 0 */
156 *len = BPF_MAXINSNS;
157 rc = get_filter(fd, NULL, len);
158 if (rc)
159 perror_msg_and_skip("getsockopt SOL_SOCKET SO_GET_FILTER");
160 printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", NULL, [%u->0]) "
161 "= 0\n",
162 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER),
163 BPF_MAXINSNS);
164
165 /* getsockopt NULL optlen - EFAULT */
166 rc = get_filter(fd, NULL, NULL);
167 printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", NULL, NULL) "
168 "= %s\n",
169 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER), errstr);
170
171 /* attach a filter */
172 rc = set_filter(fd, prog, sizeof(*prog));
173 if (rc)
174 perror_msg_and_skip("setsockopt SOL_SOCKET SO_ATTACH_FILTER");
175 printf("setsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", {len=%u, filter=",
176 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_ATTACH_FILTER),
177 prog->len);
178 print_filter();
179 printf("}, %u) = 0\n", (unsigned int) sizeof(*prog));
180
181 /* setsockopt optlen is too small - EINVAL */
182 rc = set_filter(fd, prog, sizeof(*prog) - 4);
183 printf("setsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, %u) = %s\n",
184 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_ATTACH_FILTER), prog,
185 (unsigned int) sizeof(*prog) - 4, errstr);
186
187 #ifdef SO_ATTACH_REUSEPORT_CBPF
188 rc = setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF,
189 prog, sizeof(*prog));
190 errstr = sprintrc(rc);
191 printf("setsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", {len=%u, filter=",
192 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_ATTACH_REUSEPORT_CBPF),
193 prog->len);
194 print_filter();
195 printf("}, %u) = %s\n", (unsigned int) sizeof(*prog), errstr);
196 #endif
197
198 /* query sock_filter program length -> ARRAY_SIZE(bpf_filter) */
199 *len = 0;
200 rc = get_filter(fd, efault, len);
201 printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, [0->%u]) "
202 "= %s\n",
203 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER), efault,
204 (unsigned int) ARRAY_SIZE(bpf_filter), errstr);
205
206 /* getsockopt optlen is too small - EINVAL */
207 *len = ARRAY_SIZE(bpf_filter) - 1;
208 rc = get_filter(fd, efault, len);
209 printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, [%u]) = %s\n",
210 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER), efault,
211 (unsigned int) ARRAY_SIZE(bpf_filter) - 1, errstr);
212
213 /* getsockopt optval EFAULT */
214 *len = ARRAY_SIZE(bpf_filter);
215 rc = get_filter(fd, filter + 1, len);
216 printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, [%u]) = %s\n",
217 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER),
218 filter + 1, (unsigned int) ARRAY_SIZE(bpf_filter), errstr);
219
220 /* getsockopt optlen is too large - truncated */
221 *len = ARRAY_SIZE(bpf_filter) + 1;
222 rc = get_filter(fd, filter, len);
223 printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", ",
224 fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER));
225 print_filter();
226 printf(", [%u->%d]) = %s\n",
227 (unsigned int) ARRAY_SIZE(bpf_filter) + 1, *len, errstr);
228
229 puts("+++ exited with 0 +++");
230 return 0;
231 }
232